Skip the auto shop - Our mechanics make house calls

P0412 OBD-II Trouble Code: Secondary Air Injection System Switching Valve A Circuit Malfunction

check engine light logo

P0412 code definition

Secondary Air Injection System Switching Valve A Circuit Malfunction

What the P0412 code means

P0412 is an OBD-II generic code that the engine control module (ECM) got input from the air injection system driver that the air pump or air switching valve has malfunctioned with an open or short circuit.

What causes the P0412 code?

  • The air injection switching valve voltage is too high indicating an open circuit.

  • The air injection switching valve voltage is too low indicating an short circuit.

  • The ECM sets the code from diagnostic inputs from the air injection system driver.

What are the symptoms of the P0412 code?

  • The Check Engine Light will be illuminated and the code is set in ECM memory and freeze frame.

  • The air injection system pump may not come on.

  • The engine may not have any drive symptoms except a check engine light is on.

How does a mechanic diagnose the P0412 code?

  • Scans codes and documents the freeze frame data in order to verify the problem

  • Clears the engine codes retest the air injection system for proper operation

  • Tests the air injection switching valve is controlling the air injection pump operation during tests

  • Checks the resistance of the air injection pump and air injection switching valve

  • Checks the air injection pump for proper voltage between the pins of power and ground

Common mistakes when diagnosing the P0412 code

  • Not checking for proper battery voltage above 8 volts to the air injection pump before replacing the pump for no air pumping out of it

  • Not checking the air injection pump power relay for burnt wire connections before replacing a bad air injection pump or air switching valve

How serious is the P0412 code?

  • The air injection pump system is to help lower the emissions coming out the exhaust and can cause the vehicle to fail emission testing.

  • The Check Engine Light being on causes the vehicle to fail emission testing.

  • The air injection pump should not cause any drive symptoms other than a Check Engine Light.

What repairs can fix the P0412 code?

  • Replacing the air injection pump and power relay
  • Replacing the air injection switch valve
  • Repairing the wiring to the air injection pump power relay connection

Additional comments for consideration regarding the P0412 code

Code P0412 is a problem with the air injection system driver in the ECM cannot turn on the air pump to test it during startup. A shorted air injection pump circuit can short out the air injection driver in the ECM and should be considered when diagnosing the problem.

Need help with a P0412 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Symptoms of a Bad or Failing Starter
Common signs include the engine not turning over, starter engaging but not spinning the motor, and grinding noises or smoke when starting the motor.
How Long Does a Fuel Filler Neck Last?
Getting gas from the pump to your gas tank is the only way to keep a car going. The fuel filler neck is a metal tube that is welded to the...
How Long Does a Throttle Return Spring Last?
Not all vehicles on the road feature an electronic throttle control (ETC), which is also called drive-by-wire. For vehicles that don't offer this system, they have a throttle cable instead that...


Related questions

Q: My SUV is running hard and has the Diagnostic Trouble Code P0016

Hi and thanks for contacting Your Mechanic. The code P0016 is for the crankshaft position sensor. Check the wiring harness to the sensor that is located on the bottom of the engine by the crankshaft pulley. Check for voltage and...

Q: Check engine light on

Hello. When the Check Engine Light is on in the dashboard, this is an indication that there is a problem that needs to be addressed. The only way to make the engine light go out permanently is to fix the...

Q: AT light and Check engine light on stuck in third gear.

A logical place to start is with a Check Engine Light inspection to see what codes might be set. Usually with something of this nature, codes will be present, and there will be a flow chart that should be used...